c9: sleep, dreaming, and circadian rhythms Flashcards
what is a circadian rhythm and what are the 3 types
cycle of body activity/behavior that occurs over 24 hours. diurnal, nocturnal, crepuscular
diurnal
active in day, sleep at night
nocturnal
active at night, sleep during day
crepuscular
sleep day + night, active dusk + dawn
unihemispheric sleep
one brain hemisphere is active while the other is awake. seen in dolphins
zeitgebers
external stimuli that impact circadian rhythms (ie sunlight and temperature)
free-running clock
circadian rhythm without the influence of zeitgebers
chronobiology
branch of bio studying how time of day impacts biology, physiology, and behavior of organisms
describe the study by Michel Siffre studying free-running clocks
he lived in a cave for about 3 months with no natural sunlight / way to track time. every time he slept, ate, woke up, he would call his team to notify them. it was found that the free running clock of humans can go over 24 hours. can be followed by 14 hours of sleep
what is the role of the suprachiasmatic nucleus? what effects it?
establishes and maintains circadian rhythms. impacted by light information from the eye. explains how sunlight or lack of sunlight affects our sleep cycle
melanopsin
photopigment sensitive to blue light
describe the tau mutant hamster experiement. what part of the brain is invovled?
hamsters with the tau mutation in their genes have 20 hour circadian rhythms while normal ones have 24 hours +. when the suprachiasmatic nucleus (SCN) is destroyed and given the SCN of the other type of hamster, the circadian rhythm changes
ex: 20 hours cycle hamster with tau mutation gets their SCN destroyed, given SCN of normal hamster, sleep cycle is normalized
pineal gland location and function. what controls it?
posterior to thalamus. secretes melatonin and is influenced by the SCN
polysomnography. 3 types of polysomnography
instruments used in sleep labs to measure sleep. eog, ecg, eeg
electrooculargram (EOG)
measures eye movement
electrocardiogram (ECG)
measures heart rate
electroencephalogram (EEG)
measures electrical activity in brain during sleep
types of brain waves
alpha, beta, theta, delta
what are the stages of sleep
nrem1 - 3, REM
describe n1 sleep
transition from awakeness to light sleep, muscle jerks and dream like throughts
describe n2 sleep (wave and physiological characteristics)
light sleep, neurons in brain are more synchronized, sleep spindles and k-complexes, little eye movement
sleep spindles
bursts of high freq waves
k complexes
high voltage brain spikes in the first stages of sleep
describe n3 sleep (wave type and description of wave)
slow wave sleep. theta and delta waves. no muscles movement
describe rem sleep. physiological and brain wave characteristics
rapid eye movement, high sympathetic NS activity (^ heart rate, blood pressure, breathing), high freq, low amp. brain is active, body is paralyzed
REM rebound
after sleep deprivation, time in REM increases at the next opportunity to slep
ventrolateral preoptic nucleus of the hypothalamus (VLPO)
part of the hypothalamus with inhibitory GABA sensitive neurons. promotes sleep, inhibit areas of the brain with GABA (inhibitory NT)
what does the locus coeruleus do? how is it involved in sleep
part of the brain involved with arousal/sleep due to norepinephrine. receives inhibitory NTs (GABA) in order to fall asleep. low activity when asleep, high activity when awake
where is the locus coeruleus located
dorsal pons
what is the role of the raphe nucleus and what does it do?
part of the brainstem sensitive to serotonin. role in sleep/wake cycle.
when does the raphe nucleus have high activity
wakeful hours
ponto-geniculo-occipital (PGO spike)
spike in activityof the LGN and occipital lobes during sleep. contributes to dreams
what does adenosine do?
helps to create sleepiness. longer time with no sleep = more adenosine. leads to drowsiness.
why is sleep important (3 reasons)
1) a time to get rid of waste in the brain
2) consolidation of memories, supports learning
3) unimportant connections in the brain are weakened
what did freud believe about dreams
dreams represent unconscious wishes
activation-synthesis hypothesis
theory of dreaming where the cortex tries to make sense of the high activity that occurs in the brainstem during sleep. the dreams themselves do not have any meaning
what is insomnia
difficulty staying/falling asleep
sleep apnea
difficulty or interrupted breathing while sleeping
what are the types of sleep apnea and what is the differences
obstructive sleep apnea: muscles in the back of the throat relax and block airways. physical/physiological reasons for airways being blocked
central sleep apnea: disruption in breathing due to the nervous system
what is cataplexy
when muscle paralysis that happens during sleep occurs when the person is awake normally.
what is narcolepsy
the feeling of being sleepy / loss of muscle control during waking hours. misconcepted as people randomly falling asleep
parasomnias
sleep disorders involving abnormal movements, behaviors, or experiences in sleep (I.e hallucinations)
sleep paralysis
inability to control muscles when awake in bed. can cause hallucination, “sleep paralysis demons”
what happens to people with REM sleep behavior disorder (RBD)
a person acts out their dreams while in REM
what are the two types of drugs involved in sleep
hypnotics and antihyponotics
hypnotics
drugs that help induce or maintain sleep
antihyponotics
drugs that prevents people from falling asleep
